title: Identifying antimicrobial resistance genes of human clinical relevance within Salmonella isolated from food animals in Great Britain.
abstract: OBJECTIVE
  To investigate the occurrence of antimicrobial resistance genes of human clinical relevance in Salmonella isolated from livestock in Great Britain.
  
  
  METHODS
  Two hundred and twenty-five Salmonella enterica isolates were characterized using an antimicrobial resistance gene chip and disc diffusion assays. Plasmid profiling, conjugation experiments and identification of Salmonella genomic island 1 (SGI1) were performed for selected isolates.
  
  
  RESULTS
  Approximately 43% of Salmonella harboured single or multiple antimicrobial resistance genes with pig isolates showing the highest numbers where 96% of Salmonella Typhimurium harboured one or more resistance genes. Isolates harbouring multiple resistances divided into three groups. Group 1 isolates harboured ampicillin/streptomycin/sulphonamide/tetracycline resistance and similar phenotypes. This group contained isolates from pigs, cattle and poultry that were from several serovars including Typhimurium, 4,[5],12:i:-, Derby, Ohio and Indiana. All Group 2 isolates were from pigs and were Salmonella Typhimurium. They contained a non-sul-type class 1 integron and up to 13 transferrable resistances. All Group 3 isolates harboured a class 1 integron and were isolated from all animal species included in the study. Most isolates were Salmonella Typhimurium and harboured SGI1.
  
  
  CONCLUSIONS
  Salmonella isolated from livestock was shown to harbour antimicrobial resistance genes although no or little resistance to third-generation cephalosporins or ciprofloxacin, respectively, was detected. The preponderance in pigs of multidrug-resistant Salmonella Typhimurium makes it important to introduce control measures such as improved biosecurity to ensure that they do not pass through the food chain and limit human therapeutic options.
authors.affiliation: Department of Bacteriology, Veterinary Laboratories Agency-Weybridge, New Haw, Addlestone, Surrey KT15 3NB, UK. m.anjum@vla.defra.gsi.gov.uk
authors.forename: Muna F
authors.initials: MF
authors.lastname: Anjum
authors.forename: Suman
authors.initials: S
authors.lastname: Choudhary
authors.forename: Victoria
authors.initials: V
authors.lastname: Morrison
authors.forename: Lucy C
authors.initials: LC
authors.lastname: Snow
authors.forename: Muriel
authors.initials: M
authors.lastname: Mafura
authors.forename: Peter
authors.initials: P
authors.lastname: Slickers
authors.forename: Ralf
authors.initials: R
authors.lastname: Ehricht
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Woodward
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial; D005798:Genes, Bacterial; D044404:Genomic Islands; D058751:Livestock; D046228:Microarray Analysis; D008826:Microbial Sensitivity Tests; D020411:Oligonucleotide Array Sequence Analysis; D010957:Plasmids / Q000032:analysis; D012481:Salmonella Infections, Animal / Q000382:microbiology*; D019779:Salmonella enterica / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification*; D006113:United Kingdom
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial